Scraper with integrated seal

ABSTRACT

A wiper having an integrated seal, comprising at least one dynamically stressed, first sealing lip ( 2 ) arranged in the direction of space ( 1 ) to be sealed, and at least one wiping lip ( 3 ) disposed on the side facing away from the space ( 1 ) to be sealed, as well as three, quasi-statically stressed second, third and fourth sealing lips ( 4, 5, 6 ) which are each able to be placed against at least one counter-surface ( 9 ) of mounting space ( 8 ) of the wiper with integrated seal, the second sealing lip ( 4 ) being fluid-conductive, the third and fourth sealing lips ( 5, 6 ) in each case being configured as a pressure relief valve, and sealing lips  4, 5, 6  being arranged in a series circuit in terms of technical function.

FIELD OF THE INVENTION

[0001] The present invention relates to a wiper having an integratedseal.

BACKGROUND INFORMATION

[0002] Such a wiper is known from the German Patent 296 16 242 U1. Thedouble wiper is provided for sealing a movable part with respect to apressure system, the double wiper surrounding the movable part as aring. A connection is produced between the two end faces of the doublewiper when an opening pressure in the pressure system is exceeded.

SUMMARY OF THE INVENTION

[0003] The object of the present invention is to further develop a wiperof the type indicated at the outset in such a way that the wiper withintegrated seal is relieved from pressure, and that penetration of dirtand moisture along quasi-static sealing lips in the direction of thespace to be sealed is reliably avoided.

[0004] This objective is achieved according to the invention by thefeatures of Claim 1. The dependent claims relate to advantageousrefinements.

[0005] To achieve the objective, a wiper having an integrated seal isprovided, including at least one first, dynamically stressed sealing liparranged in the direction of the space to be sealed and at least onewiping lip arranged on the side facing away from the space to be sealed,as well as three quasi-statically stressed second, third and fourthsealing lips, which are each able to be placed against at least onecounter-surface of the mounting space of the wiper with integrated seal,the second sealing lip being fluid-conductive, the third and fourthsealing lips each being formed as a pressure relief valve, and all lipsbeing arranged in a series circuit in terms of technical function. Dueto the arrangement of the quasi-statically stressed sealing lips in afunctional series circuit, they essentially have the function of alabyrinth seal and thereby effectively prevent penetration of impuritiesfrom the surroundings past the quasi-statically stressed sealing lipsinto the space to be sealed.

[0006] To avoid unacceptably great displacements of the wiper withintegrated seal within its mounting space, the second sealing lip isfluid-conductive, the third and fourth sealing lips are configured as apressure relief valve and are able to be lifted off of their respectivecounter-surfaces, for example, in response to an opening pressure ofapproximately 4 bar. The wiper is thereby prevented from beingundesirably greatly deformed and/or being forced out of its mountingspace. The third sealing lip, which is disposed functionally between thesecond and the fourth sealing lips, is of considerable importance forthe advantageous functioning of the claimed wiper. The third sealing lipprevents impurities from the surroundings from being able to penetratepast the second sealing lip into the space to be sealed. Even if theimpurities have already passed the fourth sealing lip, this still has nodisadvantageous effects on the working properties of the wiper. Becausethe impurities are reliably held back by the fourth and third sealinglips, the second sealing lip does not come into contact with theimpurities. The second sealing lip is thereby protected from wear andtear during a long service life, [and] dirt is effectively preventedfrom penetrating into the space to be sealed off.

[0007] The following remarks concern the functioning of the sealintegrated into the wiper:

[0008] Under normal operating conditions, the space to be sealed off infront of the seal integrated into the wiper is at zero pressure. Thespace may be empty, partially filled or completely filled with medium tobe sealed off; under certain conditions, the medium may also be under alow pressure of up to 4 bar. The third and fourth sealing lips abutsealingly against the wall of a housing, the wall bounding the mountingspace.

[0009] The third sealing lip is designed such that medium to be sealedis reliably held back on the side of the second sealing lip facing thespace to be sealed; a passage of fluid past the third sealing lip in thedirection of the fourth sealing lip does not take place up to theaforesaid pressure.

[0010] The second sealing lip is constructed so that it likewise abuts,but due to the structure of its surface or small interruptions in thesealing edge, allows a small volumetric flow to pass which is sufficientto relieve the pressure.

[0011] If the pressure within the space to be sealed rises above 4 bar,for example, due to leakage of a further seal upstream of the wiper withintegrated seal in the direction of the space to be sealed off, then avolumetric flow takes place past the second sealing lip in the directionof the third sealing lip, the third sealing lip, due to pressure,allowing the volumetric flow to pass in the direction of the fourthsealing lip. The fourth sealing lip lifts off briefly from itscounter-surface, so that the volumetric flow emerges visibly as leakagein the direction of the surroundings. The visible leakage is anindication that seals within the space to be sealed and/or the rod to besealed are damaged/worn out and should be replaced.

[0012] Of the quasi-statically stressed sealing lips, at least thesecond sealing lip facing the space to be sealed has a surface structurewith a roughness Ra of greater than 2 μm.

[0013] Such a surface structure can be achieved, for example, whenmanufacturing the wiper with integrated seal by forming in a mold havinga corresponding surface roughness. The surface roughness in the mold canbe produced, for example, by eroding the relevant surface.

[0014] It is likewise conceivable to produce the surface structure in amanner deviating from this, for example, by blasting the surface with agranular material of steel, non-ferrous metals, sand, ceramics orplastic having a particle size of the granular material of approximately2 to 20 μm. The surface roughness yields for the medium to be sealed afluid-conductive connection in the direction of the third sealing lipvia the second sealing lip without the second sealing lip lifting offfrom the counter-surface. Thus, the surface structure only has thepurpose of permitting a fluid-conductive connection between the space tobe sealed and the third sealing lip.

[0015] The fluid-conductive connection may also be produced or supportedby one or more interruptions, for example, by grooves running in theaxial direction in the area of the second sealing edge.

[0016] The third sealing lip arranged functionally between the secondand the fourth sealing lip preferably has a sealing edge which isbounded by two mutually intersecting conical surfaces, the first conicalsurface facing the space to be sealed forming a smaller angle with animaginary axis parallel to the axis of symmetry than the second conicalsurface facing away from the space to be sealed. The first conicalsurface preferably forms a first angle of approximately 15° with theaxis; the second conical surface preferably forms a second angle ofapproximately 45° with the axis.

[0017] The third sealing edge may be smooth or provided with a structuresimilar to the second sealing edge. Due to the comparatively flat firstangle and the steeper second angle, when the opening pressure isexceeded, the third sealing lip is deformed in such a way that themedium to be sealed passes the third sealing lip in the direction of thefourth sealing lip. It must always be ensured that a volumetric flow isable to travel past the third sealing lip in the direction of the fourthsealing lip, for example, through grooves, extending essentially in theradial direction, within the sealing ring between the third and thefourth sealing edge, or, for example, through channels within themounting space which are also not closable by an adjacent seal.

[0018] For example, the passage may be formed by preferably a pluralityof grooves, extending in the radial direction and distributed uniformlyin the circumferential direction, which form a component of the wiperwith integrated seal.

[0019] To achieve good seal tightness, the dynamically stressed, firstsealing lip preferably has a sealing edge which is sharp or providedwith a small radius of 0.2 mm maximum; the wiping lip is preferablyrounded, having a radius R=0.2. In contrast, sharp-edged wiping lipswipe off too strongly, so that an unwanted wiper leakage develops, and,for example, the medium to be sealed located on a rod is not completelyconveyed back again in the direction of the space to be sealed.

[0020] The claimed wiper with integrated seal is preferably used inconjunction with one or more upstream rod seals, for example, inbuilding machinery or other applications of mobile hydraulics.

BRIEF DESCRIPTION OF THE DRAWING

[0021] An exemplary embodiment of a wiper having an integrated seal isexplained in greater detail in the following with reference to FIGS. 1to 3, which show schematically:

[0022]FIG. 1 an exemplary embodiment of a wiper having an integratedseal in profile section as a component in the form inherent in themanufacturing process;

[0023]FIG. 2 an exemplary embodiment of a wiper having an integratedseal in top view of the side (wiper side) directed toward thesurroundings as a component in the form inherent in the manufacturingprocess;

[0024]FIG. 3 the wiper having an integrated seal from FIG. 1 in theinstalled state in conjunction with an upstream rod seal.

EXPLANATION OF THE INVENTION

[0025]FIGS. 1 and 2 show a wiper having an integrated seal. The wiperwith integrated seal has dynamically stressed, first sealing lip (2)radially on the inside, and a likewise dynamically stressed wiping lip(3) on the side facing away from space (1) to be sealed. First sealinglip (2) has a sharp sealing edge, while wiping lip (3) is designed witha radius of 0.2 mm. Wiping lip (3) is formed in such a way that, whenthe rod moves out, the wiping lip allows the very thin film of medium tobe sealed which is located on rod (16) and is not completely wiped offby first sealing lip (2), to pass in the direction of the surroundings.When rod (16) moves in, wiping lip (3) allows this lubricant film topass again in the direction of space (1) to be sealed, while impuritiesfrom the surroundings are wiped from the surface of the retracting rod.The thin film of medium to be sealed located on rod (16) lubricateswiping lip (3).

[0026] Radially on the outside, the wiper with integrated seal hasthree, quasi-statically stressed sealing lips (4, 5, 6) arranged in aseries circuit in terms of technical function. Second sealing lip (4)facing space (1) to be sealed has a surface structure with a roughnessRa of greater than 2 μm. The structure may be produced by manufacturingin a shaping mold having a corresponding surface roughness; theroughness may easily be produced in the mold by eroding.

[0027] Third sealing lip (5), arranged in the axial direction betweensecond sealing lip (4) and fourth sealing lip (6), is bounded by the twomutually intersecting conical surfaces (11, 12). First conical surface(11) forms a first angle of approximately 15° with a line runningparallel to axis (13) and touching third sealing lip (5), while secondconical surface (12) forms a second angle of approximately 45° with thisline.

[0028] To permit a passage of medium to be sealed past third sealing lip(5) in the direction of fourth sealing lip (6), in this exemplaryembodiment, three grooves (14) are provided, distributed uniformly inthe circumferential direction, which extend essentially in the radialdirection. A passage of fluid from third sealing lip (5) in thedirection of fourth sealing lip (6) is thereby also possible when thewiper with integrated seal abuts, within its mounting space (8), by wayof its areas bordering the grooves against housing (17).

[0029]FIG. 3 shows the wiper with integrated seal from FIGS. 1 and 2 inthe installed state. A further seal (15) is disposed on the side of thewiper with integrated seal facing space (1) to be sealed.

[0030] Only when further seal (15) and/or the surface of rod (16) to besealed exhibits wear and/or damage is medium to be sealed conveyed pastfurther seal (15) in the direction of the claimed wiper with integratedseal and surroundings (9). To avoid an undesirably high pressurebuild-up between further seal (15) and the claimed wiper with integratedseal, second sealing lip (4) is provided in the area of its surface witha rough, fluid-conducting structure, and third sealing lip (5) is ableto be lifted from its counter-surface (7), in the same way as fourthsealing lip (6). A costly pressure-relief bore hole in housing (17) isthereby dispensable.

What is claimed is:
 1. A wiper having an integrated seal, comprising atleast one dynamically stressed, first sealing lip (2) arranged in thedirection of space (1) to be sealed, and at least one wiping lip (3)disposed on the side facing away from the space (1) to be sealed, aswell as three quasi-statically stressed second, third and fourth sealinglips (4, 5, 6) which are each able to be placed against at least onecounter-surface (7) of mounting space (8), the second sealing lip (4)being fluid-conductive, the third and fourth sealing lips (5, 6) in eachcase being configured as a pressure relief valve, and sealing lips 4, 5,6 being arranged in a series circuit in terms of technical function. 2.The wiper as recited in claim 1, wherein of the quasi-staticallystressed sealing lips (4, 5, 6), at least the second sealing lip (4)facing the space (1) to be sealed has a surface roughness Ra of greaterthan 2 μm.
 3. The wiper as recited in claim 1, wherein the secondquasi-statically stressed sealing lip (4) has a smooth surface with aroughness of less than or equal to 2 μm, and the sealing edge has atleast one interruption in the form of a groove running in the axialdirection.
 4. The wiper as recited in one of claims 1 through 3, whereinthe fourth sealing lip (6) facing the surroundings (9) is able to belifted off from its counter-surface (7) if a maximally permittedoverpressure in the space (1) to be sealed is exceeded.
 5. The wiper asrecited in one of claims 1 through 4, wherein the third sealing lip (5),arranged functionally between the second sealing lip (4) and the fourthsealing lip (6), has a sealing edge (10) which is bounded by twomutually intersecting conical surfaces (11, 12); and the first conicalsurface (11) facing the space (1) to be sealed forms a smaller anglewith an imaginary axis parallel to axis of symmetry (13) than the secondconical surface (12) facing away from the space (1) to be sealed.
 6. Thewiper as recited in claim 5, wherein the first conical surface (11)forms a first angle of 15° with an imaginary axis parallel to the axisof symmetry (13).
 7. The wiper as recited in claim 5, wherein the secondconical surface (12) forms a second angle of 45° with an imaginary axisparallel to the axis of symmetry (13).